Latest Publications

@article{vyhlidalova_gut_2020,

title = {Gut Microbial Catabolites of Tryptophan Are Ligands and Agonists of the Aryl Hydrocarbon Receptor: A Detailed Characterization.},

author = {Barbora Vyhlídalová and Kristýna Krasulová and Petra Pečinková and Adéla Marcalíková and Radim Vrzal and Lenka Zemánková and Jan Vančo and Zdeněk Trávníček and Jan Vondráček and Martina Karasová and Sridhar Mani and Zdeněk Dvořák},

doi = {10.3390/ijms21072614},

issn = {1422-0067},

year  = {2020},

date = {2020-04-01},

journal = {International journal of molecular sciences},

volume = {21},

number = {7},

abstract = {We examined the effects of gut microbial catabolites of tryptophan on the aryl hydrocarbon receptor (AhR). Using a reporter gene assay, we show that all studied catabolites are low-potency agonists of human AhR. The efficacy of catabolites differed substantially, comprising agonists with no or low (i3-propionate, i3-acetate, i3-lactate, i3-aldehyde), medium (i3-ethanol, i3-acrylate, skatole, tryptamine), and high (indole, i3-acetamide, i3-pyruvate) efficacies. We displayed ligand-selective antagonist activities by i3-pyruvate, i3-aldehyde, indole, skatole, and tryptamine. Ligand binding assay identified low affinity (skatole, i3-pyruvate, and i3-acetamide) and very low affinity (i3-acrylate, i3-ethanol, indole) ligands of the murine AhR. Indole, skatole, tryptamine, i3-pyruvate, i3-acrylate, and i3-acetamide induced CYP1A1 mRNA in intestinal LS180 and HT-29 cells, but not in the AhR-knockout HT-29 variant. We observed a similar CYP1A1 induction pattern in primary human hepatocytes. The most AhR-active catabolites (indole, skatole, tryptamine, i3-pyruvate, i3-acrylate, i3-acetamide) elicited nuclear translocation of the AhR, followed by a formation of AhR-ARNT heterodimer and enhanced binding of the AhR to the CYP1A1 gene promoter. Collectively, we comprehensively characterized the interactions of gut microbial tryptophan catabolites with the AhR, which may expand the current understanding of their potential roles in intestinal health and disease.},

note = {Place: Switzerland},

keywords = {*Gastrointestinal Microbiome/drug effects, Animals, Aryl hydrocarbon receptor, Aryl Hydrocarbon/*agonists/*metabolism, Basic Helix-Loop-Helix Transcription Factors/*agonists/*metabolism, Cell Line, Cytochrome P-450 CYP1A1/genetics, Gene Expression, Genes, Genetic, Humans, Indoles, Ligands, Metabolic Networks and Pathways, Mice, Microbiome, Promoter Regions, Protein Binding, Protein Multimerization, Receptors, Reporter, tryptophan, Tryptophan/*metabolism, Tumor},

pubstate = {published},

tppubtype = {article}

}

@article{topinka_dna_2008,

title = {DNA adducts formation and induction of apoptosis in rat liver epithelial 'stem-like' cells exposed to carcinogenic polycyclic aromatic hydrocarbons.},

author = {Jan Topinka and Sona Marvanová and Jan Vondrácek and Oksana Sevastyanova and Zuzana Nováková and Pavel Krcmár and Katerina Pencíková and Miroslav Machala},

doi = {10.1016/j.mrfmmm.2007.09.004},

issn = {0027-5107},

year  = {2008},

date = {2008-02-01},

journal = {Mutation research},

volume = {638},

number = {1-2},

pages = {122–132},

abstract = {The bipotent liver progenitor cells, so called oval cells, may participate at the early stages of hepatocarcinogenesis induced by chemical carcinogens. Unlike in mature parenchymal cells, little is known about formation of DNA adducts and other genotoxic events in oval cells. In the present study, we employed spontaneously immortalized rat liver WB-F344 cell line, which is an established in vitro model of oval cells, in order to study genotoxic effects of selected carcinogenic polycyclic aromatic hydrocarbons (PAHs). With exception of dibenzo[a,l]pyrene, and partly also benzo[g]chrysene and benz[a]anthracene, all other PAHs under the study induced high levels of CYP1A1 and CYP1B1 mRNA. In contrast, we observed distinct genotoxic and cytotoxic potencies of PAHs. Dibenzo[a,l]pyrene, and to a lesser extent also benzo[a]pyrene, benzo[g]chrysene and dibenzo[a,e]pyrene, formed high levels of DNA adducts. This was accompanied with accumulation of Ser-15 phosphorylated form of p53 protein and induction of apoptosis. Contrary to that, benz[a]anthracene, chrysene, benzo[b]fluoranthene and dibenzo[a,h]anthracene induced only low amounts of DNA adducts formation and minimal apoptosis, without exerting significant effects on p53 phosphorylation. Finally, we studied effects of 2,4,3',5'-tetramethoxystilbene and fluoranthene, inhibitors of CYP1B1 activity, which plays a central role in metabolic activation of dibenzo[a,l]pyrene. In a dose-dependent manner, both compounds inhibited apoptosis induced by dibenzo[a,l]pyrene, suggesting that it interferes with the metabolic activation of the latter one. The present data show that in model cell line sharing phenotypic properties with oval cells, PAHs can be efficiently metabolized to form ultimate genotoxic metabolites. Liver progenitor cells could be thus susceptible to this type of genotoxic insult, which makes WB-F344 cell line a useful tool for studies of genotoxic effects of organic contaminants in liver cells. Our results also suggest that, unlike in mature hepatocytes, CYP1B1 might be a primary enzyme responsible for formation of DNA adducts in liver progenitor cells.},

note = {Place: Netherlands},

keywords = {*Apoptosis, Animals, Aryl Hydrocarbon Hydroxylases/genetics, Cells, Cultured, Cytochrome P-450 CYP1A1/genetics, Cytochrome P-450 CYP1B1, DNA Adducts/*metabolism, Inbred F344, Liver/*cytology, Messenger/analysis, Polycyclic Aromatic Hydrocarbons/*pharmacology, Rats, RNA, Stem Cells/*metabolism},

pubstate = {published},

tppubtype = {article}

}

@article{andrysik_aryl_2007,

title = {The aryl hydrocarbon receptor-dependent deregulation of cell cycle control induced by polycyclic aromatic hydrocarbons in rat liver epithelial cells.},

author = {Zdenek Andrysík and Jan Vondrácek and Miroslav Machala and Pavel Krcmár and Lenka Svihálková-Sindlerová and Anne Kranz and Carsten Weiss and Dagmar Faust and Alois Kozubík and Cornelia Dietrich},

doi = {10.1016/j.mrfmmm.2006.10.004},

issn = {0027-5107},

year  = {2007},

date = {2007-02-01},

journal = {Mutation research},

volume = {615},

number = {1-2},

pages = {87–97},

abstract = {Disruption of cell proliferation control by polycyclic aromatic hydrocarbons (PAHs) may contribute to their carcinogenicity. We investigated role of the aryl hydrocarbon receptor (AhR) in disruption of contact inhibition in rat liver epithelial WB-F344 'stem-like' cells, induced by the weakly mutagenic benz[a]anthracene (BaA), benzo[b]fluoranthene (BbF) and by the strongly mutagenic benzo[a]pyrene (BaP). There were significant differences between the effects of BaA and BbF, and those of the strongly genotoxic BaP. Both BaA and BbF increased percentage of cells entering S-phase and cell numbers, associated with an increased expression of Cyclin A and Cyclin A/cdk2 complex activity. Their effects were significantly reduced in cells expressing a dominant-negative AhR mutant (dnAhR). Roscovitine, a chemical inhibitor of cdk2, abolished the induction of cell proliferation by BbF. However, neither BaA nor BbF modulated expression of the principal cdk inhibitor involved in maintenance of contact inhibition, p27(Kip1), or pRb phosphorylation. The strongly mutagenic BaP induced apoptosis, a decrease in total cell numbers and significantly higher percentage of cells entering S-phase than either BaA or BbF. Given that BaP induced high levels of Cyclin A/cdk2 activity, downregulation of p27(Kip1) and hyperphosphorylation of pRb, the accumulation of cells in S-phase was probably due to cell proliferation, although S-phase arrest due to blocked replication forks can not be excluded. Both types of effects of BaP were significantly attenuated in dnAhR cells. Transfection of WB-F344 cells with siRNA targeted against AhR decreased induction of Cyclin A induced by BbF or BaP, further supporting the role of AhR in proliferative effects of PAHs. This suggest that activation of AhR plays a significant role both in disruption of contact inhibition by weakly mutagenic PAHs and in genotoxic effects of BaP possibly leading to enhanced cell proliferation. Thus, PAHs may increase proliferative rate and the likelihood of fixation of mutations.},

note = {Place: Netherlands},

keywords = {Animals, Apoptosis/drug effects, Aryl Hydrocarbon/antagonists & inhibitors/genetics/*metabolism, Base Sequence, Benz(a)Anthracenes/toxicity, Benzo(a)pyrene/toxicity, Cell Cycle Proteins/metabolism, Cell Cycle/*drug effects/*physiology, Cell Line, Cell Proliferation/drug effects, Cyclin A/metabolism, Cyclin-Dependent Kinase 2/metabolism, Cytochrome P-450 CYP1A1/genetics, Epithelial Cells/cytology/drug effects/metabolism, Fluorenes/toxicity, Gene Expression/drug effects, Hepatocytes/cytology/*drug effects/*metabolism, Messenger/genetics/metabolism, Multiprotein Complexes, Mutagens/toxicity, Mutation, Polycyclic Aromatic Hydrocarbons/*toxicity, Rats, Receptors, RNA, Small Interfering/genetics},

pubstate = {published},

tppubtype = {article}

}

@article{vondracek_7h-dibenzocgcarbazole_2006,

title = {7H-Dibenzo[c,g]carbazole and 5,9-dimethyldibenzo[c,g]carbazole exert multiple toxic events contributing to tumor promotion in rat liver epithelial 'stem-like' cells.},

author = {Jan Vondrácek and Lenka Svihálková-Sindlerová and Katerina Pencíková and Pavel Krcmár and Zdenek Andrysík and Katerina Chramostová and Sona Marvanová and Zuzana Valovicová and Alois Kozubík and Alena Gábelová and Miroslav Machala},

doi = {10.1016/j.mrfmmm.2005.11.005},

issn = {0027-5107},

year  = {2006},

date = {2006-04-01},

journal = {Mutation research},

volume = {596},

number = {1-2},

pages = {43–56},

abstract = {Immature liver progenitor cells have been suggested to be an important target of hepatotoxins and hepatocarcinogens. The goal of the present study was to assess the impact of 7H-dibenzo[c,g]carbazole (DBC) and its tissue-specific carcinogenic N-methyl (N-MeDBC) and 5,9-dimethyl (DiMeDBC) derivatives on rat liver epithelial WB-F344 cells, in vitro model of liver progenitor cells. We investigated the cellular events associated with both tumor initiation and promotion, such as activation of aryl hydrocarbon receptor (AhR), changes in expression of enzymes involved in metabolic activation of DBC and its derivatives, effects on cell cycle, cell proliferation/apoptosis and inhibition of gap junctional intercellular communication (GJIC). N-MeDBC, a tissue-specific sarcomagen, was only a weak inhibitor of GJIC or inducer of AhR-mediated activity, and it did not affect either cell proliferation or apoptosis. DBC was efficient GJIC inhibitor, while DiMeDBC manifested the strongest AhR inducing activity. Accordingly, DiMeDBC was also the most potent inducer of cytochrome P450 1A1 (CYP1A1) and CYP1A2 expression among the three compounds tested. Both DBC and DiMeDBC induced expression of CYP1B1 and aldo-keto reductase 1C9 (AKR1C9). N-MeDBC failed to significantly upregulate CYP1A1/2 and it only moderately increased CYP1B1 or AKR1C9. Only the potent liver carcinogens, DBC and DiMeDBC, caused a significant increase of p53 phosphorylation at Ser15, an increased accumulation of cells in S-phase and apoptosis at micromolar concentrations. In addition, DiMeDBC was found to stimulate cell proliferation of contact-inhibited WB-F344 cells at 1 microM concentration, which is a mode of action that might further contribute to its hepatocarcinogenicity. The present data seem to suggest that the AhR activation, induction of enzymes involved in metabolic activation, inhibition of GJIC or stimulation of cell proliferation might all contribute to the hepatocarcinogenic effects of DBC and DiMeDBC.},

note = {Place: Netherlands},

keywords = {Animals, Aryl Hydrocarbon Hydroxylases/genetics, Base Sequence, Carbazoles/*toxicity, Carcinogens/*toxicity, Cell Death/drug effects, Cytochrome P-450 CYP1A1/genetics, Cytochrome P-450 CYP1A2/genetics, Cytochrome P-450 CYP1B1, DNA Primers, Epithelial Cells/drug effects/*pathology, Inbred F344, Liver/*cytology/drug effects, Methylation, Molecular Structure, Mutagens, Rats, Reverse Transcriptase Polymerase Chain Reaction},

pubstate = {published},

tppubtype = {article}

}